Field of the Invention:
The invention relates to a plug for optical fiber cables, having an optical fiber cable seated in a plug tube, as well as a cover cap seated on a light exit side of the plug. The invention also relates to a socket part into which such a plug can be inserted.
A plug for optical fiber cables is described, for example, in German Utility Model G 90 10 357.2. The plug has a plug tube, which is penetrated coaxially by a holding bore into which the optical fiber cable is inserted. A cable duct tapers inside the plug tube toward an end surface in three sections having diameters which correspond to diameters of an outer sheath, of an inner sheath and of a fiber core of the optical fiber cable. The plug tube is injected from plastic in one piece and has a cylindrical basic body which merges at an end surface into a centering pin and which tapers to a plug pin. Only the optical fiber remains seated in the plug pin.
Optical fiber cables having plugs are being used evermore frequently as communication cables. In the meantime, optical fiber cables having plugs are being used as connecting cables between devices processing optical signals, such as compact disc players and digital audio tape recorders, for example. Moreover, experiments are being conducted in motor vehicles with regard to communication by individual components through optical signals. For that purpose, the necessary control and receiving units have optical IN/OUT connections that include, for example, a plug socket in which an optical fiber cable terminates inside the device. The connection between such devices is performed through the use of an optical fiber cable having two plugs which are fitted at the end and can be used to produce a plug-in connection in a plug receptacle or in a holding bore of a socket part.
A high mechanical stability of the plug-in connection is essential to enable signals to be transmitted largely free from loss and interference. Moreover, it is mandatory that the coupling surface, that is to say the light exit or light entrance side of the optical fiber plug, is not contaminated, scratched or the like, because otherwise disadvantages occur in the signal transmission characteristic of the optical fiber. That can go so far that it is no longer possible at all to transmit optical signals.
It is therefore necessary for the coupling surface of the optical fiber plug to be effectively protected against moisture and contamination starting from the finished processing of the complete plug and during transportation and laying up to plugging into a socket part. Moreover, the tight plug-in connection is required for some applications of such an optical fiber plug.
In order to fulfill those conditions, it has been customary in the interim to push a cover cap onto the plug side of such an optical fiber plug for the purpose of protection during transportation. The cover cap is pulled off and subsequently thrown away after transportation. Special head or radial seals are used for sealing in the case of such known optical fiber plugs.